Wheel constructions for agricultural vehicles and the like off-road vehicles, are known which include a circular wheel rim which provides respective axially inner and outer flanges which each provide a seat for a tyre bead of a floatation tyre which is fitted to a radially outer, or “tyre side” of the rim. In the example of U.S. Pat. No. 5,560,686, such a wheel construction is disclosed which further includes a disc by means of which the wheel is securable to a hub of the vehicle, the disc being connected to a radially inner side of the rim and the disc and rim being separable. This invention is though applicable to wheels in which the rim and disc are permanently connected together e.g. by welding.
In this specification, by “floatation tyre” we mean a wide (axially long) tyre which spreads loads thus reducing, e.g. soil, compaction, when the vehicle is driven on a non-road surface.
Agricultural vehicle wheel constructions are known which include a wheel rim with axially inner and outer portions which each provide a tyre bead seat flange, and an adjoining frusto-conical connecting surface which extends axially towards the mid-portion where there is central well. The tyre bead seat flange, and typically at least a part of the connecting surface, together provide a seat for the tyre. The connecting surface adjoins a circumferentially extending side part, which side part extends to and adjoins the mid-portion of the rim.
It has been found that with such existing rims, the service life of the rims may be insufficient because structural stresses which occur in the area where the side parts adjoin the mid-region, can lead to premature failures of the rims.